U1: C2 Enzymes

Question 1

Allosteric effect

Answer 1

Multiple binding sites, and each bind affects other active site affinity

Question 2

Inhibition

a. feedback
b. reversible
c. irreversible

Answer 2

1. product regulates enzyme activity (- feedback)
2. reversible
   
   1. competative: inhibitor and substrate compete for active site
   2. noncompetative: inhibitor binds to nonactive site, allosteric site and changes active site conformation
3. active site permanetly unavailable or altered

Question 3

Competative vs noncompetative inhibition

a. binds
b. can be overcome?
c. Km change or Vmax change?

Answer 3

1. Binds
   
   1. inhibitor binds to active site
   2. inhibitor binds to allosteric site
2. overcome
   
   1. yes, by adding more substrates
   2. no
3. Km change or Vmax change
   
   1. increase Km= less affinity for substrate
   2. decrease Vmax

Question 4

Zymogen

Answer 4

inactive enzyme, only active once catalyzed

(trypsinogen -> trypsin)

Function is to protect the parent organisms (digestive enzyme)

Question 5

Enzyme Key concepts

1. Ea
2. rxn rate
3. eq constant
4. gibbs free energy
5. change self

Answer 5

1. decrease activation energy
2. increase rate of rxn (kinetics)
3. do not change equil constant
4. not affect overall change in gibbs free energy
5. not changed or consumed in the rxn

Question 6

Cofactor

Answer 6

1. nonprotein moelcule required by enzyme to be effective
2. either small metal ions, small organic groups like vitamins, coenzymes

Question 7

apoenzyme vs holoenzyme

Answer 7

1. apo: w/o cofactor, enzyme is unable to perform certain necessary rxns.
2. holo: w/ cofactor, enzyme can perform certain necessary rxns.

Question 8

Propeties that affect Kinetics x 3

Answer 8

1. temperature (human body 37 Celcius)
2. pH (stomach 2, pancreas 8.5, blood 7.4)
3. [substrate] & [enzyme]

http://learning.covcollege.ac.uk/content/Jorum/MET_Enzyme-inhibition_LM-1.2/files/asset12.gif

• V_max= saturation of enzyme substrate complex, [s]>[e]
• 1/2 V_max= K_m=[s] = 1/2 Enyzmes full
• when …
  
  • [s] < K_{m ,} Rxn rate effected
  • [s] > K_m , Rxn , Approach V max
  • K_m inversely proportional to Enzyme Affinity